The letters I, Q, and Z weren't used in the ABC section, and I, O, Q, U and Z were not used as year letters (although I and Z were valid in Eire). Q denoted a specialregistration such as a kit car or an imported vehicle of non-provable age.

In 1983, the system had reached Y-registration, and had run out of letters. A new system was introduced, which simply changed the position of the three letters and the year letter:

A123 BCD

This continued in the same vein as the old scheme until 1999, when six-monthly letter changes were introduced. S was August 1998, T was March 1999, and from then on, changes occurred every March and September.

The AB is the regional code, although a different code to the old system. The two numbers are a date code: March 20XX will get XX, September 20XX will get XX+50, so this system works until 2049. The CDE bit is randomly or sequentially issued. This time around, Z will be a valid letter.

See http://www.wolfbane.com/vreg.htm for more details including regional codes.

Since 1 September, 2001, United Kingdom licence plates have followed the following format:

LLXX RRRLL is a two letter local identifierXXIs a two number age identifierRRR are three random letters

Local Identifier

The first of the two letters in this part of the plate represent the region the vehicle was first registered in. The second part denotes a particular DVLA office. The letters 'Q', 'I' and 'Z' will not be used in this part of the plate. The registration areas are as follows:

Age Identifier

Vehicles registered between September and February are marked with the last two digits of the year; for example, a vehicle registered in December 2005 will have the age identifier '05'. If it is registered between March and September, then 50 is added to this number; a car registered in June 2006 will be marked as 56.

Random Letters

Randomly generated letters with some restrictions. The letters 'I' and 'Q' will not be used (although 'Z' will), and combinations that could cause offence (including 'SEX') are also not permitted.